Ethnicity and race influence the folate status response to controlled folate intakes in young women

Assessing a Fermented Whey Beverage Biofortified with Folate as a Potential Folate Source for Humans

Folate, a vital water-soluble vitamin (B9), requires specific attention as its recommended daily intake frequently is not reached in countries without mandatory fortification. In this regard, biofortification with microorganisms like Bifidobacterium and Streptococcus offers a compelling approach for enhancing food with natural folates. A randomized, nonblinded, and monocentric human pilot study is conducted to assess the bioavailability of a folate-biofortified fermented whey beverage, comprising 3 intervention days and a controlled replenishment phase before and during the assay. Folate plasma concentration (5-CH3-H4folate) is determined using a stable isotope dilution assay and LC-MS/MS detection. Biokinetic parameters (cmax and tmax) are determined, and areas under the curve (AUC) normalized to the basal folate plasma concentration are calculated. An average bioavailability of 17.1% in relation to the 5-CH3-H4folate supplement, ranging from 0% to 39.8%, is obtained. These results reiterate the significance of additional research into folate bioavailability in general and dairy products. Further investigations are warranted into folate-binding proteins (FBP) and other potential limiting factors within the food and individual factors. In summary, biofortification via fermentation emerges as a promising avenue for enhancing the natural folate content in dairy and other food products.

Cohort profile: Biomarkers related to folate-dependent one-carbon metabolism in colorectal cancer recurrence and survival - the FOCUS Consortium

PURPOSE

The overarching goal of the FOCUS (biomarkers related to folate-dependent one-carbon metabolism in colorectal cancer (CRC) recurrence and survival) Consortium is to unravel the effect of folate and folate-mediated one-carbon metabolism (FOCM) biomarkers on CRC prognosis to provide clinically relevant advice on folate intake to cancer patients and define future tertiary prevention strategies.

PARTICIPANTS

The FOCUS Consortium is an international, prospective cohort of 2401 women and men above 18 years of age who were diagnosed with a primary invasive non-metastatic (stages I-III) CRC. The consortium comprises patients from Austria, two sites from the Netherlands, Germany and two sites from the USA. Patients are recruited after CRC diagnosis and followed at 6 and 12 months after enrolment. At each time point, sociodemographic data, data on health behaviour and clinical data are collected, blood samples are drawn.

FINDINGS TO DATE

An increased risk of cancer recurrences was observed among patients with higher compared with lower circulating folic acid concentrations. Furthermore, specific folate species within the FOCM pathway were associated with both inflammation and angiogenesis pathways among patients with CRC. In addition, higher vitamin B6 status was associated with better quality of life at 6 months post-treatment.

FUTURE PLANS

Better insights into the research on associations between folate and FOCM biomarkers and clinical outcomes in patients with CRC will facilitate the development of guidelines regarding folate intake in order to provide clinically relevant advice to patients with cancer, health professionals involved in patient care, and ultimately further tertiary prevention strategies in the future. The FOCUS Consortium offers an excellent infrastructure for short-term and long-term research projects and for combining additional biomarkers and data resulting from the individual cohorts within the next years, for example, microbiome data, omics and multiomics data or CT-quantified body composition data.

A Systematic Review of Literature on the Representation of Racial and Ethnic Minority Groups in Clinical Nutrition Interventions

The racial and ethnic disparities in diet-related chronic diseases are major concerns. This systematic review examines the extent to which diet-induced changes in health outcomes, such as cardiometabolic, inflammation, cancer, bone health, and kidney function outcomes, etc., have been reported and discussed by race or ethnicity in randomized trials with 2 or more diet arms that recruited both minority and non-Hispanic White groups. Databases (i.e., PubMed, Cochrane Library, and Web of Science) were searched up to August 2021. Thirty-four studies that discussed effects of defined dietary interventions on health outcomes by racial or ethnic minority group compared with non-Hispanic Whites were included in the systematic review (PROSPERO registration number: CRD42021229256). Acute trials and those with 1 diet arm that accounted for race or ethnicity in their analyses and studies that focused on a single racial or ethnic group were discussed separately. Most studies were conducted in Black compared with White adults testing effects of energy restriction, macronutrient modification, sodium reduction, or variations of the Dietary Approaches to Stop Hypertension (DASH) diet on cardiometabolic outcomes. There was limited focus on other minority groups. Evidence suggests greater blood pressure reduction for Black adults compared with Whites particularly with DASH (or similar) diets. Overall, there was limited consideration for group-specific eating patterns and diet acceptability. Overall risk of bias was low. With emerging precision nutrition initiatives that aim to optimize metabolic responses in population subgroups through tailored approaches, it is imperative to ensure adequate representation of racial and ethnic subgroups for addressing health disparities. Factors that help explain variability in responses such as socioecological context should be included and adequately powered. Given the racial and ethnic disparities in chronic diseases, studying the adoption, maintenance, and effectiveness of dietary interventions on health outcomes among different groups is critical for developing approaches that can mitigate diet-related health disparities.

DNA methylation changes in cord blood and the developmental origins of health and disease – a systematic review and replication study

Background

Environmental exposures in utero which modify DNA methylation may have a long-lasting impact on health and disease in offspring. We aimed to identify and replicate previously published genomic loci where DNA methylation changes are attributable to in utero exposures in the NutriGen birth cohort studies Alliance.

Methods

We reviewed the literature to identify differentially methylated sites of newborn DNA which are associated with the following five traits of interest maternal diabetes, pre-pregnancy body mass index (BMI), diet during pregnancy, smoking, and gestational age. We then attempted to replicate these published associations in the Canadian Healthy Infant Longitudinal Development (CHILD) and the South Asian birth cohort (START) cord blood epigenome-wide data.

Results

We screened 68 full-text articles and identified a total of 17 cord blood epigenome-wide association studies (EWAS) of the traits of interest. Out of the 290 CpG sites reported, 19 were identified in more than one study; all of them associated with maternal smoking. In CHILD and START EWAS, thousands of sites associated with gestational age were identified and maintained significance after correction for multiple testing. In CHILD, there was differential methylation observed for 8 of the published maternal smoking sites. No other traits tested (i.e., folate levels, gestational diabetes, birthweight) replicated in the CHILD or START cohorts.

Conclusions

Maternal smoking during pregnancy and gestational age are strongly associated with differential methylation in offspring cord blood, as assessed in the EWAS literature and our birth cohorts. There are a limited number of reported methylation sites associated in more than two independent studies related to pregnancy. Additional large studies of diverse populations with fine phenotyping are needed to produce robust epigenome-wide data in order to further elucidate the effect of intrauterine exposures on the infants’ methylome.

The evolution of human skin pigmentation involved the interactions of genetic, environmental, and cultural variables

The primary biological role of human skin pigmentation is as a mediator of penetration of ultraviolet radiation (UVR) into the deep layers of skin and the cutaneous circulation. Since the origin of Homo sapiens, dark, protective constitutive pigmentation and strong tanning abilities have been favored under conditions of high UVR and represent the baseline condition for modern humans. The evolution of partly depigmented skin and variable tanning abilities has occurred multiple times in prehistory, as populations have dispersed into environments with lower and more seasonal UVR regimes, with unique complements of genes and cultural practices. The evolution of extremes of dark pigmentation and depigmentation has been rare and occurred only under conditions of extremely high or low environmental UVR, promoted by positive selection on variant pigmentation genes followed by limited gene flow. Over time, the evolution of human skin pigmentation has been influenced by the nature and course of human dispersals and modifications of cultural practices, which have modified the nature and actions of skin pigmentation genes. Throughout most of prehistory and history, the evolution of human skin pigmentation has been a contingent and non-deterministic process.

The Antioxidant Role of One-Carbon Metabolism on Stroke

One-carbon (1C) metabolism is a metabolic network that is centered on folate, a B vitamin; it integrates nutritional signals with biosynthesis, redox homeostasis, and epigenetics. This metabolic pathway also reduces levels of homocysteine, a non-protein amino acid. High levels of homocysteine are linked to increased risk of hypoxic events, such as stroke. Several preclinical studies have suggested that 1C metabolism can impact stroke outcome, but the clinical data are unclear. The objective of this paper was to review preclinical and clinical research to determine whether 1C metabolism has an antioxidant role on stroke. To accomplish the objective, we searched for publications using the following medical subject headings (MeSH) keywords: antioxidants, hypoxia, stroke, homocysteine, one-carbon metabolism, folate, methionine, and dietary supplementation of one-carbon metabolism. Both pre-clinical and clinical studies were retrieved and reviewed. Our review of the literature suggests that deficiencies in 1C play an important role in the onset and outcome of stroke. Dietary supplementation of 1C provides beneficial effects on stroke outcome. For stroke-affected patients or individuals at high risk for stroke, the data suggest that nutritional modifications in addition to other therapies could be incorporated into a treatment plan.

Environmental UVR Levels and Skin Pigmentation Gene Variants Associated with Folate and Homocysteine Levels in an Elderly Cohort

Ultraviolet radiation (UVR) is a ubiquitous exposure which may contribute to decreased folate levels. Skin pigmentation mediates the biological effect of UVR exposure, but its relationship to folate levels is unexamined. Interactions may exist between UVR and pigmentation genes in determining folate status, which may, in turn, impact homocysteine levels, a potential risk factor for multiple chronic diseases. Therefore, independent and interactive influences of environmental UVR and genetic variants related to skin pigmentation (MC1R-rs1805007, IRF4-rs12203592 and HERC2-rs12913832) on folate (red blood cell (RBC) and serum) and homocysteine levels were examined in an elderly Australian cohort (n = 599). Genotypes were assessed by RT/RFLP-PCR, and UVR exposures were assessed as the accumulated erythemal dose rate accumulated over 4 months (4M-EDR). Multivariate analysis found significant negative associations between 4M-EDR and RBC folate (p < 0.001, β = −0.19), serum folate (p = 0.045, β = −0.08) and homocysteine levels (p < 0.001, β = −0.28). Significant associations between MC1R-rs1805007 and serum folate levels (p = 0.020), and IRF4-rs12203592 and homocysteine levels (p = 0.026) occurred but did not remain significant following corrections with confounders. No interactions between 4M-EDR and pigmentation variants in predicting folate/homocysteine levels were found. UVR levels and skin pigmentation-related variants are potential determinants of folate and homocysteine status, although, associations are mixed and complex, with further studies warranted.

Knowledge and intake of folic acid among teachers of childbearing age in the State of Qatar: a cross-sectional study

OBJECTIVES

To assess the knowledge and intake of folic acid among teachers of childbearing age and to identify barriers to folic acid intake.

SETTING

Governmental schools, which included 14 primary models, 29 primary, 14 preparatory and 16 secondary schools. The proportion of teachers in each stratum was then determined, and a stratified random sampling design had been used with proportional allocation.

STUDY DESIGN

Cross-sectional study PARTICIPANTS: A total of 406 non-pregnant teachers of childbearing age enrolled in the study. A validated questionnaire in the Arabic language was used.

RESULTS

The overall response rate was 98%. About 34.6% reported the optimal period in which they should take folic acid, 28.3% reported the correct intake duration and only 29.5% could name food rich in folic acid. Friends and healthcare providers were the main sources of information for the participants; however, 44% said that they did not receive enough information from their healthcare providers.

CONCLUSION

There is a lack of knowledge and poor intake of folic acid among the participants. In particular, they lacked information about the appropriate time to start folic acid supplementations, the duration of intake and the folic acid-rich food. The most common reason being the limited advice given by their healthcare providers.Awareness campaigns are recommended to emphasise the role of healthcare providers in counselling women about the proper use of folic acid before pregnancy.

Intake of niacin, folate, vitamin B-6, and vitamin B-12 through young adulthood and cognitive function in midlife: the Coronary Artery Risk Development in Young Adults (CARDIA) study

Background: Epidemiologic evidence regarding niacin, folate, vitamin B-6, and vitamin B-12 intake in relation to cognitive function is limited, especially in midlife.Objective: We hypothesize that higher intake of these B vitamins in young adulthood is associated with better cognition later in life.Design: This study comprised a community-based multicenter cohort of black and white men and women aged 18-30 y in 1985-1986 (year 0, i.e., baseline) from the Coronary Artery Risk Development in Young Adults (CARDIA) study (n = 3136). We examined participants' CARDIA diet history at years 0, 7, and 20 to assess nutrient intake, including dietary and supplemental B vitamins. We measured cognitive function at year 25 (mean ± SD age: 50 ± 4 y) through the use of the Rey Auditory Verbal Learning Test (RAVLT) for verbal memory, the Digit Symbol Substitution Test (DSST) for psychomotor speed, and a modified Stroop interference test for executive function. Higher RAVLT and DSST scores and a lower Stroop score indicated better cognitive function. We used multivariable-adjusted linear regressions to estimate mean differences in cognitive scores and 95% CIs.Results: Comparing the highest quintile with the lowest (quintile 5 compared with quintile 1), cumulative total intake of niacin was significantly associated with 3.92 more digits on the DSST (95% CI: 2.28, 5.55; P-trend < 0.01) and 1.89 points lower interference score on the Stroop test (95% CI: -3.10, -0.68; P-trend = 0.05). Total folate was associated with 2.56 more digits on the DSST (95% CI: 0.82, 4.31; P-trend = 0.01). We also found that higher intakes of vitamin B-6 (quartile 5 compared with quartile 1: 2.62; 95% CI: 0.97, 4.28; P-trend = 0.02) and vitamin B-12 (quartile 5 compared with quartile 1: 2.08; 95% CI: 0.52, 3.65; P-trend = 0.02) resulted in better psychomotor speed measured by DSST scores.Conclusion: Higher intake of B vitamins throughout young adulthood was associated with better cognitive function in midlife.

Assessing the association between natural food folate intake and blood folate concentrations: a systematic review and Bayesian meta-analysis of trials and observational studies

Folate is found naturally in foods or as synthetic folic acid in dietary supplements and fortified foods. Adequate periconceptional folic acid intake can prevent neural tube defects. Folate intake impacts blood folate concentration; however, the dose-response between natural food folate and blood folate concentrations has not been well described. We estimated this association among healthy females. A systematic literature review identified studies (1 1992-3 2014) with both natural food folate intake alone and blood folate concentration among females aged 12-49 years. Bayesian methods were used to estimate regression model parameters describing the association between natural food folate intake and subsequent blood folate concentration. Seven controlled trials and 29 observational studies met the inclusion criteria. For the six studies using microbiologic assay (MA) included in the meta-analysis, we estimate that a 6% (95% Credible Interval (CrI): 4%, 9%) increase in red blood cell (RBC) folate concentration and a 7% (95% CrI: 1%, 12%) increase in serum/plasma folate concentration can occur for every 10% increase in natural food folate intake. Using modeled results, we estimate that a natural food folate intake of ≥ 450 μg dietary folate equivalents (DFE)/day could achieve the lower bound of an RBC folate concentration (~ 1050 nmol/L) associated with the lowest risk of a neural tube defect. Natural food folate intake affects blood folate concentration and adequate intakes could help women achieve a RBC folate concentration associated with a risk of 6 neural tube defects/10,000 live births.

Vitamin B and its derivatives for diabetic kidney disease

BACKGROUND

Diabetes is a leading cause of end-stage kidney disease (ESKD) mainly due to development and progression of diabetic kidney disease (DKD). In absence of definitive treatments of DKD, small studies showed that vitamin B may help in delaying progression of DKD by inhibiting vascular inflammation and endothelial cell damage. Hence, it could be beneficial as a treatment option for DKD.

OBJECTIVES

To assess the benefits and harms of vitamin B and its derivatives in patients with DKD.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 29 October 2012 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials comparing vitamin B or its derivatives, or both with placebo, no treatment or active treatment in patients with DKD. We excluded studies comparing vitamin B or its derivatives, or both among patients with pre-existing ESKD.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias and extracted data. Results were reported as risk ratio (RR) or risk differences (RD) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) with 95% CI for continuous outcomes. Statistical analyses were performed using the random-effects model.

MAIN RESULTS

Nine studies compared 1354 participants randomised to either vitamin B or its derivatives with placebo or active control were identified. A total of 1102 participants were randomised to single vitamin B derivatives, placebo or active control in eight studies, and 252 participants randomised to multiple vitamin B derivatives or placebo. Monotherapy included different dose of pyridoxamine (four studies), benfotiamine (1), folic acid (1), thiamine (1), and vitamin B12 (1) while combination therapy included folic acid, vitamin B6, and vitamin B12 in one study. Treatment duration ranged from two to 36 months. Selection bias was unclear in three studies and low in the remaining six studies. Two studies reported blinding of patient, caregiver and observer and were at low risk of performance and detection bias, two studies were at high risk bias, and five studies were unclear. Attrition bias was high in one study, unclear in one study and low in seven studies. Reporting bias was high in one study, unclear in one study, and low in the remaining seven studies. Four studies funded by pharmaceutical companies were judged to be at high risk bias, three were at low risk of bias, and two were unclear.Only a single study reported a reduction in albuminuria with thiamine compared to placebo, while second study reported reduction in glomerular filtration rate (GFR) following use of combination therapy. No significant difference in the risk of all-cause mortality with pyridoxamine or combination therapy was reported. None of the vitamin B derivatives used either alone or in combination improved kidney function: increased in creatinine clearance, improved the GFR; neither were effective in controlling blood pressure significantly compared to placebo or active control. One study reported a significant median reduction in urinary albumin excretion with thiamine treatment compared to placebo. No significant difference was found between vitamin B combination therapy and control group for serious adverse events, or one or more adverse event per patient. Vitamin B therapy was reported to well-tolerated with mild side effects in studies with treatment duration of more than six months. Studies of less than six months duration did not explicitly report adverse events; they reported that the drugs were well-tolerated without any serious drug related adverse events. None of the included studies reported cardiovascular death, progression from macroalbuminuria to ESKD, progression from microalbuminuria to macroalbuminuria, regression from microalbuminuria to normoalbuminuria, doubling of SCr, and quality of life. We were not able to perform subgroup or sensitivity analyses or assess publication bias due to insufficient data.

AUTHORS' CONCLUSIONS

There is an absence of evidence to recommend the use of vitamin B therapy alone or combination for delaying progression of DKD. Thiamine was found to be beneficial for reduction in albuminuria in a single study; however, there was lack of any improvement in kidney function or blood pressure following the use of vitamin B preparations used alone or in combination. These findings require further confirmation given the limitations of the small number and poor quality of the available studies.

The causal effect of red blood cell folate on genome-wide methylation in cord blood: a Mendelian randomization approach

Background

Investigation of the biological mechanism by which folate acts to affect fetal development can inform appraisal of expected benefits and risk management. This research is ethically imperative given the ubiquity of folic acid fortified products in the US. Considering that folate is an essential component in the one-carbon metabolism pathway that provides methyl groups for DNA methylation, epigenetic modifications provide a putative molecular mechanism mediating the effect of folic acid supplementation on neonatal and pediatric outcomes.

Results

In this study we use a Mendelian Randomization Unnecessary approach to assess the effect of red blood cell (RBC) folate on genome-wide DNA methylation in cord blood. Site-specific CpG methylation within the proximal promoter regions of approximately 14,500 genes was analyzed using the Illumina Infinium Human Methylation27 Bead Chip for 50 infants from the Epigenetic Birth Cohort at Brigham and Women’s Hospital in Boston. Using methylenetetrahydrofolate reductase genotype as the instrument, the Mendelian Randomization approach identified 7 CpG loci with a significant (mostly positive) association between RBC folate and methylation level. Among the genes in closest proximity to this significant subset of CpG loci, several enriched biologic processes were involved in nucleic acid transport and metabolic processing. Compared to the standard ordinary least squares regression method, our estimates were demonstrated to be more robust to unmeasured confounding.

Conclusions

To the authors’ knowledge, this is the largest genome-wide analysis of the effects of folate on methylation pattern, and the first to employ Mendelian Randomization to assess the effects of an exposure on epigenetic modifications. These results can help guide future analyses of the causal effects of periconceptional folate levels on candidate pathways.

Erythrocyte folate status and serum iron levels in patients undergoing hemodialysis

The present study was aimed to evaluate erythrocyte folate and the iron levels in diabetes and hypertension patients treated with/without hemodialysis. The effects of erythropoietin and iron treatment as well as vitamin supplementation on measured parameters were considered. The 67 controls consisted of healthy subjects (n = 22), hypertensive subjects (n = 22), and diabetic subjects (n = 23) without any renal disorder. According to primary renal disorders, the patients undergoing hemodialysis (n = 68) were classified into four groups as diabetic nephropathy, hypertensive nephropathy, reflux nephropathy or interstitial nephritis, and renal insufficiency depending on other causative factors. The mean value of erythrocyte folate levels of all patients undergoing hemodialysis was higher than the healthy control group (P < 0.05). Erythrocyte folate levels in hypertensive and diabetic nephropathy patients were higher than their own hypertensive or diabetic controls and also healthy controls (both, P < 0.05). Serum iron levels of all subgroups in hemodialysis patients were found to be similar with healthy controls (all, P > 0.05). The only significance observed within the subgroups was between diabetic controls and diabetic nephropathy patients (P < 0.05). None of the treatment or supplementation of erythropoietin, iron and vitamin affected erythrocyte folate levels (all, P > 0.05). The increase in erythrocyte folate status of patients with end stage renal diseases might be the result of sum or individual effects of causative factors such as renal pathology, compensation mechanism against renal anemia, or routine folate supplementation.

Mutational analysis of the MTHFR gene in breast cancer patients of Pakistani population

OBJECTIVES

Since methylenetetrahydrofolate reductase (MTHFR) maintains the balance of circulating folate and methionine and blocks the formation of homocysteine, its regulation in relation to different cancers has extensively been studied in different populations. However, information on Pakistani breast cancer patients is lacking. The MTHFR gene has two most common mutations that are single nucleotide additions which result in change of amino acids C677T to Ala222val and A1298C to Glu429Ala.

METHODOLOGY

110 sporadic breast patients with no prior family history of cancer or any other type of genetic disorders along with 110 normal individuals were screened for mutations in exons 1 to exon 9 using single strand conformational polymorphism, RFLP and sequencing analyzer.

RESULTS

The p values for the 677CC, 677CT, and 677TT genotypes were 0.223, 0.006, and 0.077, respectively. Those for the 1298AA, 1298AC, and 1298CC genotypes were 0.555, 0.009, and 0.003, respectively.

CONCLUSIONS

We found an overall a significant, weak inverse association between breast cancer risk and the 677TT genotype and an inverse association with the 1298C variant. These results for MTHFR polymorphism might be population specific in sporadic breast cancer affected patients but many other factors need to be excluded before making final conclusions including folate intake, population and disease heterogeneity.

Folate-status response to a controlled folate intake in nonpregnant, pregnant, and lactating women

BACKGROUND

Folate dose-response studies in women of childbearing age who consumed a folic acid (FA)-containing multivitamin in the era of FA fortification are lacking.

OBJECTIVE

We sought to investigate folate-status response to a known folate dose comprising an FA-containing prenatal supplement (750 μg/d) plus natural food folate (400 μg/d) in third-trimester pregnant women, lactating women 5-15 wk postpartum, and nonpregnant women.

DESIGN

Pregnant (n = 26), lactating (n = 28), and nonpregnant (n = 21) women consumed the study folate dose under controlled intake conditions for 10-12 wk. Blood, urine, and breast milk were collected at baseline, study midpoint, and study end.

RESULTS

Study-end serum total folate concentrations averaged ~30 ng/mL and did not differ by physiologic group (P = 0.876). Study-end urinary folate excretion represented ~9-43% of total folate intake and ranged from 100 to 500 μg/d. Third-trimester pregnant women excreted less urinary folate than did lactating (P = 0.075) and nonpregnant (P < 0.001) women. Lactating women excreted less (P < 0.001) urinary FA than did nonpregnant women. Breast-milk total folate concentrations remained constant (P = 0.244; 61.8 ng/mL at study end), whereas breast-milk FA concentrations increased (P = 0.003) to 24.1 ng/mL at study end.

CONCLUSIONS

The consumption of the study folate dose yielded a supranutritional folate status regardless of the physiologic state. Based on urinary folate excretion, folate use was greatest to least: pregnant > lactating > nonpregnant women. Breast-milk folate species were responsive to maternal folate intake, and FA made up ~40% of breast-milk total folate at study end. These findings warrant revisiting prenatal supplement FA formulation in populations exposed to FA-fortification programs.

Acculturation factors are associated with folate intakes among Mexican American women

Folic acid can prevent neural tube defects (NTD). Hispanic women have a higher prevalence of NTD than non-Hispanic white (NHW) women and consume less folic acid. Among Hispanics, acculturation has been associated with lower intakes of natural folate. It is unknown if this same relationship is seen for fortified foods. This article describes the associations of acculturation factors with usual folate intakes from foods and supplements and compares the proportion that meets recommended intakes of folic acid of US Mexican American (MA) women with those of NHW women. For US NHW and MA women aged 15-44 y (n = 3167), usual folate intakes (i.e., natural food folate, folic acid from food, total folic acid [fortified foods plus supplements], and total folate) were estimated using measurement error models from NHANES 2001-2008. Compared with NHW women, MA women did not differ in their intake of natural food folate or folic acid from food. Similarly, compared with NHW women (332 ± 17.3 μg/d), the mean total usual folic acid intakes were lower among MA women who reported speaking Spanish (224 ± 24.9 μg/d) but not for MA women who reported speaking English (283 ± 36.2 μg/d). MA women were more likely than NHW women to consume a total folic acid intake <400 μg/d. MA women with lower acculturation factors were the most likely to have an intake <400 μg/d compared to NHW women. Public health efforts should focus on increasing total folic acid intake among MA women, emphasizing those with lower acculturation factors (e.g., MA women who report speaking Spanish).

Folate bioavailability: implications for establishing dietary recommendations and optimizing status

The addition of folic acid to the US food supply, along with the critical role of folate in certain health outcomes, has intensified worldwide interest in the bioavailability of folate. Bioavailability is a function of absorptive and postabsorptive processes, which in turn are influenced by diet, individuality, and complex diet-host interactions. As such, it is unlikely that a single bioavailability figure will accurately reflect food folate bioavailability from every diet for every person. Although there is broad agreement that naturally occurring food folate is not as bioavailable as folic acid, questions remain as to the extent of these differences, particularly within the context of a whole diet. This article 1) summarizes and integrates bioavailability estimates derived from studies that use whole-diet approaches; 2) highlights the influences of genetics, ethnicity-race, and sex as postabsorptive bioavailability modifiers; and 3) discusses the adequacy of the US folate Recommended Dietary Allowance in achieving folate sufficiency in select subpopulations.

Polymorphisms in methionine synthase, methionine synthase reductase and serine hydroxymethyltransferase, folate and alcohol intake, and colon cancer risk

BACKGROUND/AIMS

We examined associations among folate and alcohol intake, single nucleotide polymorphisms (SNPs) in genes involved in one-carbon metabolism, and colon cancer risk.

METHODS

Colon cancer cases (294 African-Americans and 349 whites) were frequency matched to population controls (437 African-Americans and 611 whites) by age, race and sex from 33 North Carolina counties from 1996 to 2000. Folate and alcohol intakes were collected by dietary interview. Five SNPs were genotyped using DNA from whole blood: SHMT C1420T; MTRR A66G; MTR A2756G, and the previously-reported MTHFR C677T and MTHFR A1298C. Adjusted odds ratios (OR) and 95% CI were calculated using logistic regression.

RESULTS

An inverse association was observed for SHMT TT genotype as compared to CC genotype in whites (OR = 0.6, 95% CI = 0.4, 1.0), but not in African Americans. Inverse associations were observed for high folate intake in individuals carrying 0 or 1 variant allele [OR 0.2 (95% CI 0.06-0.8) for African-Americans; OR 0.2 (95% CI 0.1-0.6) for whites] compared to low folate intake. Modest interactions between these SNPs and alcohol or folate intakes were observed.

CONCLUSIONS

Our results are consistent with other findings and provide needed data on these associations among African-Americans.

How well do blood folate concentrations predict dietary folate intakes in a sample of Canadian lactating women exposed to high levels of folate? An observational study

Background

In 1998, mandatory folic acid fortification of white flour and select cereal grain products was implemented in Canada with the intention to increase dietary folate intakes of reproducing women. Folic acid fortification has produced a dramatic increase in blood folate concentrations among reproductive age women, and a reduction in neural tube defect (NTD)-affected pregnancies. In response to improved blood folate concentrations, many health care professionals are asking whether a folic acid supplement is necessary for NTD prevention among women with high blood folate values, and how reliably high RBC folate concentrations predict folate intakes shown in randomized controlled trials to be protective against NTDs. The objective of this study was to determine how predictive blood folate concentrations and folate intakes are of each other in a sample of well-educated lactating Canadian women exposed to high levels of synthetic folate.

Methods

The relationship between blood folate concentrations and dietary folate intakes, determined by weighed food records, were assessed in a sample of predominantly university-educated lactating women (32 ± 4 yr) at 4-(n = 53) and 16-wk postpartum (n = 55).

Results

Median blood folate concentrations of all participants were well above plasma and RBC folate cut-off levels indicative of deficiency (6.7 and 317 nmol/L, respectively) and all, except for 2 subjects, were above the cut-off for NTD-risk reduction (>906 nmol/L). Only modest associations existed between total folate intakes and plasma (r = 0.46, P < 0.001) and RBC (r = 0.36, P < 0.01) folate concentrations at 16-wk postpartum. Plasma and RBC folate values at 16-wk postpartum correctly identified the quartile of folate intake of only 26 of 55 (47%) and 18 of 55 (33%) of subjects, respectively. The mean RBC folate concentration of women consuming 151–410 μg/d of synthetic folate (2^nd quartile of intake) did not differ from that of women consuming >410 μg/d (3^rd and 4^th quartile).

Conclusion

Folate intakes, estimated by food composition tables, and blood folate concentrations are not predictive of each other in Canadian lactating women exposed to high levels of folate. Synthetic intakes > 151–410 μg/d in these women produced little additional benefit in terms of maximizing RBC content. More studies are needed to examine the relationship between blood folate concentration and NTD risk. Until data from such studies are available, women planning a pregnancy should continue to consume a daily folic acid supplement of 400 μg.

Does food group consumption vary by differences in socioeconomic, demographic, and lifestyle factors in young adults? The Bogalusa Heart Study

OBJECTIVE

To examine if food group consumption varies by differences in socioeconomic, demographic, and lifestyle factors in young adults from a semirural setting in Louisiana.

DESIGN

Cross-sectional.

SUBJECTS

Young adults (n=1,266, 74% European American, 26% African American; 39% men, 61% women) aged 20 to 38 years, enrolled in the Bogalusa Heart Study.

MEASURES

Food group consumption was assessed by a food frequency questionnaire. Socioeconomic (eg, income and education), demographic (eg, age, sex, and ethnicity), and lifestyle (eg, marital status and physical activity) information was obtained by a self-administered questionnaire and the subjects were stratified according to these groups.

STATISTICAL ANALYSES

Analysis of covariance (adjusted for covariates) was used to detect differences in the mean servings of food groups consumed per day between the various socioeconomic, demographic, and lifestyle groups.

RESULTS

Compared to income$45,000 had lower consumption of burgers/sandwiches (P<0.05) and those with income levels from $30,001 to $45,000 had lower consumption of mixed dishes (P<0.05). Intake of cereals/breads (P<0.05), dairy products (P<0.01), fruits/100% fruit juices (P<0.001), and vegetables (P<0.001) was higher in subjects with >12 years of education. European-American men consumed more servings of dairy products (P<0.05) and sweetened beverages (P<0.05) than African-American men. European-American women consumed more servings of dairy products (P<0.05), vegetables (P<0.05), and fats (P<0.05) than African-American women. African Americans (men and women) consumed more servings of fruits/100% fruit juices (P<0.0001) than European Americans (men and women), respectively. Married individuals consumed more servings of snacks/desserts (P<0.05), but fewer servings of alcoholic beverages (P<0.0001) than those who were unmarried. Active individuals consumed more servings of fruits/100% fruit juices (P<0.05) and fewer servings of burgers/sandwiches (P<0.05) than inactive individuals.

CONCLUSIONS

These findings suggest that food group consumption varies by socioeconomic, demographic, and lifestyle factors in young adults from a semirural setting. Food and nutrition professionals who encounter diverse populations need to consider the influence of income, education, sex, ethnicity, marital status, and physical activity on food consumption patterns when planning diets, nutrition education programs, and interventions for young adults.

Global leukocyte DNA methylation is similar in African American and Caucasian women under conditions of controlled folate intake

DNA methylation is an epigenetic feature that may modify disease risk, and can be influenced by folate status as well as by methylenetetrahydrofolate reductase (MTHFR) C677T genotype. The aim of this study was to investigate the influence of ethnicity/race on global leukocyte DNA methylation under conditions of controlled folate intake. Caucasian (n = 14) and African American (n = 14) women (18 - 45 y) possessing the MTHFR 677CC genotype consumed a folate restricted diet (135 mug/d as dietary folate equivalents, DFE) for 7 week followed by folate treatment with 400 or 800 microg DFE/d for 7 week. Global leukocyte DNA methylation was assessed via the cytosine extension assay at baseline (wk 0), after folate restriction (wk 7) and after folate treatment (wk 14). Ethnicity/race was not a determinant of global leukocyte DNA methylation. No differences (p > 0.05) were detected in DNA methylation between African American and Caucasian women at baseline or any other study time point. In addition, folate intake did not modify global leukocyte DNA methylation. These data suggest that global leukocyte DNA methylation does not differ between Caucasian and African American women and that short-term folate restriction is not sufficient to modify methylation content in young women with the MTHFR 677CC genotype.

Association of MTHFR gene polymorphisms with breast cancer survival

Background

Two functional single nucleotide polymorphisms (SNPs) in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, C677T and A1298C, lead to decreased enzyme activity and affect chemosensitivity of tumor cells. We investigated whether these MTHFR SNPs were associated with breast cancer survival in African-American and Caucasian women.

Methods

African-American (n = 143) and Caucasian (n = 105) women, who had incident breast cancer with surgery, were recruited between 1993 and 2003 from the greater Baltimore area, Maryland, USA. Kaplan-Meier survival and multivariate Cox proportional hazards regression analyses were used to examine the relationship between MTHFR SNPs and disease-specific survival.

Results

We observed opposite effects of the MTHFR polymorphisms A1298C and C677T on breast cancer survival. Carriers of the variant allele at codon 1298 (A/C or C/C) had reduced survival when compared to homozygous carriers of the common A allele [Hazard ratio (HR) = 2.05; 95% confidence interval (CI), 1.05–4.00]. In contrast, breast cancer patients with the variant allele at codon 677 (C/T or T/T) had improved survival, albeit not statistically significant, when compared to individuals with the common C/C genotype (HR = 0.65; 95% CI, 0.31–1.35). The effects were stronger in patients with estrogen receptor-negative tumors (HR = 2.70; 95% CI, 1.17–6.23 for A/C or C/C versus A/A at codon 1298; HR = 0.36; 95% CI, 0.12–1.04 for C/T or T/T versus C/C at codon 677). Interactions between the two MTHFR genotypes and race/ethnicity on breast cancer survival were also observed (A1298C, p_interaction = 0.088; C677T, p_interaction = 0.026).

Conclusion

We found that the MTHFR SNPs, C677T and A1298C, were associated with breast cancer survival. The variant alleles had opposite effects on disease outcome in the study population. Race/ethnicity modified the association between the two SNPs and breast cancer survival.

Dietary and other lifestyle correlates of serum folate concentrations in a healthy adult population in Crete, Greece: a cross-sectional study

Background

Folate has emerged as a key nutrient for optimising health. Impaired folate status has been identified as a risk factor for cardiovascular disease, various types of cancers, and neurocognitive disorders. The study aimed at examining the distribution and determinants of serum folate concentrations in a healthy adult population in Crete, Greece.

Methods

A cross-sectional sample of 486 healthy adults (250 men, 236 women) aged 39 ± 14 years, personnel of the Medical School and the University Hospital of Crete in Greece, was examined. Serum folate and vitamin B₁₂ concentrations were measured by microbiological assay, and total homocysteine was determined fluorometrically and by high-pressure liquid chromatography. Lifestyle questionnaires were completed, and nutrient intakes and food consumption were assessed by 24-h dietary recalls. Multivariate analyses were performed using SPSS v10.1.

Results

The geometric mean (95% confidence interval) concentrations of serum folate were 15.6 μmol/l (14.6–16.8) in men and 19.2 μmol/l (17.9–20.7) in women (p < 0.001). Inadequate folate levels (≤7 nmol/l) were present in 6.8% of men and 2.1% of women (p < 0.001). Approximately 76% of men and 87% of women did not meet the reference dietary intake for folate (400 μg/day). Serum folate was inversely related to total homocysteine levels (p < 0.001). Increased tobacco and coffee consumption were associated with lower folate concentrations (p < 0.05 for both) but these associations disappeared after controlling for nutrient intakes. In multivariate analysis, intakes of MUFA, fibre, calcium, magnesium, folate, and vitamins A, E, C, B₁, and B₆ were positively associated with serum folate. Consumption of potatoes, legumes, fruits, and vegetables were favourably related to the serum folate status.

Conclusion

Serum folate concentrations were associated with various demographic, lifestyle and dietary factors in healthy Cretan adults. Large-scale epidemiological studies should be conducted within the general Greek adult population to assess the prevalence of impaired folate status and further examine associations with dietary patterns and chronic disease risk. Considering the importance of folate in health maintenance, it is important to increase the public's awareness of modifiable lifestyle patterns and diet and tobacco use in particular, which may be associated with improved folate status.

Trends in serum folate, RBC folate, and circulating total homocysteine concentrations in the United States: analysis of data from National Health and Nutrition Examination Surveys, 1988-1994, 1999-2000, and 2001-2002

Folate intakes increased dramatically after folic acid fortification. We investigated the changes in serum folate, RBC folate, and total homocysteine (tHcy) concentrations utilizing data from National Health and Nutrition Examination Surveys (NHANES) 1988-2002. NHANES 1988-2002 were based on a stratified, multistage, probability sampling design conducted among civilian U.S. residents. The current study included 17,144, 17,213, and 11,415 measurements for serum folate, RBC folate, and tHcy, respectively. Overall, geometric mean serum folate concentrations were 149.6 and 129.8% higher in 1999-2000 and 2001-2002, respectively, than in 1988-1994 (P < 0.0001). Sex-, age-, and race-ethnicity-adjusted serum folate was significantly lower in 2001-2002 than in 1999-2000 (10.4%, P < 0.0002). The prevalence of low serum folate decreased from 18.4% in 1988-1994 to 0.8% in 1999-2000 and to 0.2% in 2001-2002 (P < 0.0001). RBC folate increased from 391 nmol/L in 1988-1994 to 618 nmol/L in 1999-2000, and to 611 nmol/L in 2001-2002. Consequently, the prevalence of low RBC folate decreased from 45.8% in 1988-1994 to 7.3% in 1999-2000 and to 7.1% in 2001-2002 (P < 0.0001). Although, RBC folate status improved after folic acid fortification in all race-ethnicities, the prevalence of low RBC folate ( approximately 20.5%) continues to be high in non-Hispanic blacks. Age-, sex-, and race-ethnicity-adjusted tHcy declined from 9.5 micromol/L in 1988-1994 to 7.6 mumol/L in 1999-2000 and to 7.9 micromol/L in 2001-2002. Although folic acid fortification contributed to significant improvement in folate status, serum folate concentrations have declined recently. This may be attributable to lower folic acid intakes.

Effects of short-term folic acid and/or riboflavin supplementation on serum folate and plasma total homocysteine concentrations in young Japanese male subjects

OBJECTIVE

To investigate the effects of short-term folic acid and/or riboflavin supplementation on serum folate and plasma plasma total homocysteine (tHcy) concentrations in young Japanese male subjects.

DESIGN

In a double blind, randomized controlled trial.

INTERVENTION

Subjects were randomly assigned to one of four groups and received a placebo (control group), 800 microg/day folic acid (FA group), 8.4 mg/day riboflavin (R group), or both (FAR group) for 2 weeks.

SETTING

Tokyo, Japan.

SUBJECTS

In total, 32 healthy male volunteers aged 20-29 years.

RESULTS

At the end of the 2 week supplementation period, the tHcy concentration decreased significantly in the FA group. Serum folate concentrations had increased between 2.7 and 2.0-fold in the FA and FAR groups, respectively, but the mean within-group changes in serum folate and plasma tHcy concentrations did not differ between these two groups. At the end of the study, alanine amino transferase was decreased in the R and FAR groups, while alanine amino transferase was increased in the FA group.

CONCLUSION

Supplementation with folic acid, 800 microg/day, for 2 weeks, increased the serum and red blood cell folate concentrations and decreased the plasma tHcy concentrations in healthy young male subjects. Riboflavin supplementation may have blunted the effect of folic acid, which resulted in a diminished reduction of tHcy in our subjects.

The glycine N-methyltransferase (GNMT) 1289 C->T variant influences plasma total homocysteine concentrations in young women after restricting folate intake

Glycine N-methyltransferase (GNMT) is a key regulatory protein in folate metabolism, methionine availability, and transmethylation reactions. Perturbations in GNMT may lead to aberrations in homocysteine metabolism, a marker of numerous pathologies. The primary objective of this study was to examine the influence of the GNMT 1289 C-->T alone, and in combination with the methylenetetrahydrofolate reductase (MTHFR) 677 C-->T variant, on plasma total homocysteine concentrations in healthy young women (n = 114). Plasma total homocysteine was measured at baseline (wk 0) and after 2 wk of controlled folate restriction (135 microg/d as dietary folate equivalents). Plasma homocysteine concentrations did not differ among the GNMT C1289T genotypes at baseline. However, after folate restriction, women with the GNMT 1289 TT genotype (n = 16) had higher (P = 0.019) homocysteine concentrations than women with the CT (n = 51) or CC (n = 47) genotype. The influence of the GNMT 1289 C-->T variant on homocysteine was dependent on the MTHFR C677T genotype. In subjects with the MTHFR 677 CC genotype, homocysteine was greater (P < or = 0.05) for GNMT 1289 TT subjects relative to 1289 CT or CC subjects. However, in subjects with the MTHFR 677 TT genotype, plasma homocysteine concentrations did not differ among the GNMT C1289T genotypes. Overall, these data suggest that the GNMT 1289 C-->T polymorphism influences plasma homocysteine and is responsive to folate intake.

Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999-2000

BACKGROUND

Mandatory folic acid fortification of cereal-grain products was introduced in the United States in 1998 to decrease the risk that women will have children with neural tube defects.

OBJECTIVE

The objective was to determine the effect of folic acid fortification on concentrations of serum and red blood cell (RBC) folate, serum vitamin B-12, and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in the US population.

DESIGN

Blood was collected from a nationally representative sample of approximately 7300 participants aged > or = 3 y in the National Health and Nutrition Examination Survey (NHANES) during 1999-2000 and was analyzed for these B vitamin-status indicators. The results were compared with findings from the prefortification survey NHANES III (1988-1994).

RESULTS

The reference ranges (5th-95th percentiles) were 13.1-74.3 nmol/L for serum folate, 347-1167 nmol/L for RBC folate, and 179-738 pmol/L for serum vitamin B-12. For plasma tHcy and MMA, the reference ranges for serum vitamin B-12-replete participants with normal serum creatinine concentrations were 3.2-10.7 mumol/L and 60-210 nmol/L, respectively. The prevalence of low serum folate concentrations (<6.8 nmol/L) decreased from 16% before to 0.5% after fortification. In elderly persons, the prevalence of high serum folate concentrations (>45.3 nmol/L) increased from 7% before to 38% after fortification; 3% had marginally low serum vitamin B-12 concentrations (<148 pmol/L) and 7% had elevated plasma MMA concentrations (>370 nmol/L). Seventy-eight percent of the US population had plasma tHcy concentrations <9 micromol/L.

CONCLUSIONS

Every segment of the US population appears to benefit from folic acid fortification. Continued monitoring of B vitamin concentrations in the US population is warranted.

A long-term controlled folate feeding study in young women supports the validity of the 1.7 multiplier in the dietary folate equivalency equation

The presence of folic acid in enriched cereal grain products and the higher bioavailability of folic acid than food folate led to the expression of the 1998 folate RDA, 400 microg/d, as dietary folate equivalents (DFE). DFE are defined as: mug natural food folate + 1.7 x microg synthetic folic acid. The 1.7 multiplier was based on assumptions that added folic acid was 85% available and food folate was 50% available. The 85/50 ratio also inferred that the bioavailability of food folate was approximately 60% relative to added folic acid. The objective of this long-term controlled feeding study was to assess the dietary folate equivalency of folic acid. After a 2-wk period of folate restriction, women (n = 42, 18-45 y old) consumed either 400 or 800 microg DFE/d derived from various combinations of food folate and folic acid for 12 wk. Folic acid was converted to DFE using the 1.7 multiplier from the DFE calculation and was consumed with a meal throughout the treatment period. Folate status response to the various treatments was assessed during wk 12-14. Serum folate, RBC folate, and plasma total homocysteine did not differ among the 400 microg DFE/d groups or among the 800 microg DFE/d groups. In contrast, consumption of 800 microg DFE/d led to higher (P </= 0.05) serum and RBC folate than consumption of 400 microg DFE/d. These data support the validity of the 1.7 multiplier in the DFE equation and suggest that food folate bioavailability is approximately 60% that of added folic acid when consumed as part of a mixed diet.